1. Field of the Invention
This invention relates to machine tools and more particularly to a turret punch press equipped with a laser cutting and marking assembly.
2. Prior Art
Automatic computer controlled turret punch machine tools are known to the art wherein the machine tool is provided with computer controlled work piece movement gripping devices which move the workpiece accurately in both x and y axis directions with respect to a punching station. Movement of the workpiece is generally done, at least in part, over a stationry work table portion surrounding the lower turret of the machine tool. Controls and mechanisms for such workpiece movement have become so sophisticated that workpiece movement speeds in excess of 1500 inches per minute on either axis are known. Additionally, punch ram movements on the order of 400 strokes a minute are also known. Thus, modern computer controlled turret punches represent highly versatile machine tools capable of quickly and accurately providing sheet metal and plastics with desired punched out areas. However, the versatility of such turret punches is limited in that material can be removed from the workpiece only by a punching type operation. Thus, when large areas of the workpiece are to be removed, or when the workpiece is to be subdivided into a number of separable workpieces, or when relatively long or large diameter cuts are to be made, this can be accomplished only by a series of slightly overlapping punching type metal removal operations. This is generally referred to as "nibbling". Although such overlapping material removal operations can effectively be used to increase the versatility of a punch, those operations have, at times, undesired consequences, such as formation of burred edges, inability to produce highly accurate, smooth arcuate side edges, relative slowness of operation, etc. As a result, many cutting or shearing type operations are performed by other machine tools in a subsequent operation which requires additional workpiece handling.
In order to increase the ability of automatic punching equipment to provide large and/or irregularly shaped holes in the workpiece, it has been suggested to equip the punch press with a plasma arc cutting torch. See for example U.S. Pat. No. 4,063,059. Such cutting torches are frequently undesirable in that they have inherent disadvantages such as relatively large kirfs, ragged edges and large heat distort areas adjacent the cut.
Although it has been known to provide metal cutting machines utilizing techniques other than plasma arc torches, including laser beam cutting machines, such devices have not previously been integrated with machine tool turret punches.
Among other reasons for the art to have not attempted a combination of a laser cutting device and a machine tool turret punch is the fact that during punching operations, the entire machine tool is subjected to pounding vibrations. Since lasers are highly sensitive devices, it has hitherto been thought that they would not be adaptable for use in high shock and vibration locations.
It would, therefore, be an advance in the art to combine a laser cutting tool with a machine tool computer controlled turret punch.
Moreover, it is often times desirable to surface mark a workpiece at a precisely predetermined position. Punching machines are primarily designed for material removal and are not generally capable of surface marking. The same is true with respect to cutting lasers.
It would, therefore, be a further advance in the art to provide a combination turret punch and laser cutting assembly having capabilities of surface marking of workpieces.
Additionally, it would represent a major advance in the art of machine tools to provide a single machine tool capable of high speed, high accuracy workpiece punching, cutting, and surface marking wherein all functions are controllable from a central automatic control and wherein workpiece movement is accomplished by a single mechanism so as to eliminate the necessity of workpiece handling between operations.